The present invention relates to a multi-turret lathe with two opposed spindles comprising two spindles coaxially opposed to each other and a plurality of tool turrets co-operable with the spindles for machining a workpiece.
The lathe with two opposed spindles comprising two spindles coaxially opposing to each other is known in the art. The conventional lathes hold one end of a workpiece to machine the workpiece and that end cannot be machined while it is being held. In the lathe with two opposed spindles, however, the partially machined workpiece can be transferred from one spindle to the other, and each of the ends of the workpiece which has been held by a chuck of either one of the spindles can be machined on the same machine.
If the lathe with two opposed spindles includes a plurality of tool turrets, two different machining operations can simultaneously be performed for two workpieces held by two different spindles. This improves the efficiency of working. The tool turrets may be provided with rotary tools such as drills and milling cutters, tailstocks, supporting rollers which support the workpiece at the periphery thereof, and the like. When these tools are mounted on the tool turrets in an appropriate combination, the workpiece can be subjected to a broad type of machining operations.
A lathe with two opposed spindles in a prior art is classified into two-spindle and two-turret type and two-spindle and three-turret type. The two-spindle and two-turret type lathe comprises two spindles and two turrets each cooperating with the corresponding spindle for machining a workpiece. In such an arrangement, a single workpiece held by one of the spindles can be machined by use of two tool turrets. For example, when the workpiece is held at one side by a chuck of one of the spindles, the opposite side of the workpiece may be held by a tailstock which is mounted on a tool turret cooperating with the other spindle for lathe-turning. However, this disables the machining of a workpiece on the other spindle.
In the two-spindle and three-turret type lathe, usually, the third turret is movable from a position in which a workpiece supported by the first spindle is to be machined to another position in which a workpiece supported by the second spindle is to be machined. Each of the first and second spindles can cooperate with two turrets to machine the workpiece as necessary. For example, a workpiece held by one spindle can be lathe-turned or drilled while simultaneously machining the external and internal diameters of the workpiece by use of two turrets on the other spindle.
If a workpiece held by one spindle is machined by use of two tool turrets, a reaction force on the workpiece being machined can be balanced by cutting the workpiece at two positions opposite to each other about the axis of the spindle. This enables various types of machining operations such as machining a shaft by use of a tailstock mounted on one turret, simultaneous cutting of external and internal diameters and so on which could not be performed by the conventional one-turret lathes with one spindle. Furthermore, the efficiency of working can be improved since the workpiece can be machined simultaneously at two positions.
However, the three-turret lathes with two spindles used in the prior art can only use one turret for one spindle when the third turret is used cooperating with the other spindle. Thus, machining using two turrets cannot be performed on the one spindle until the working with the third turret has been completed.
The present invention provides a multi-turret lathe with two opposed spindles which can more effectively machine a workpiece. The present invention can economically realize broad types of machining by providing a reasonable structure in which a tool can be moved and positioned in a direction (Y-axis) orthogonal to the direction of spindle (Z-axis) and the direction of tool cutting (X-axis).
A lathe with two opposed spindles of the present invention comprises: a first spindle 2; a second spindle 4 located opposite to the first spindle on a spindle axis of the first spindle and movable and positionable in a direction of the spindle axis; and a set of two tool turrets 8a and 8c which machines a workpiece cooperating with the first spindle, and another set of two tool turrets 8b and 8d which machines a workpiece cooperating with the second spindle. The two tool turrets in each of the sets are disposed opposite to each other at a forward-downward side and a backward-upward side of the spindle axis B, respectively.
It may be most preferred that each of the four tool turrets in two sets is mounted on a tool slide which is movable and positionable in the directions of Z-axis and X-axis. It may be further preferred that each of the four tool turrets is independently movable from a position to machine a workpiece held by the first spindle to another position to machine a workpiece held by the second spindle. At least one of two opposing tool turrets in one set may include a device for driving rotary tools such as a drill and a milling cutter.
In a more preferred lathe with two opposed spindles of the present invention, may include a second spindle 4 and a first spindle immovable in a direction of spindle axis, the second spindle 4 and the first spindle may be arranged next to each other as viewed from an operator on the machine base. One of the two tool turrets cooperating with each of the spindles may be disposed at a backward-upward side of the spindle axis B while the other of the two tool turrets be disposed at a forward-downward side of the spindle axis. All of the four tool turrets may be movable and positionable in a direction of spindle axis and in a direction perpendicular to the spindle axis.
In a further preferred lathe with two opposed spindles of the present invention, may comprise a device for moving and positioning tool turrets disposed on a backward-upward side of the spindle axis (B), in a direction of Y-axis, and the backward tool turret may include a device for driving a rotary tool. In such a structure, the tool turret disposed on a forward-downward side of the spindle axis B may include no Y-axis moving and positioning device.